Disazo metal chelate compounds for optical recording media

ABSTRACT

A metal chelate compound of a dis-azo compound represented by the following formula (I) with a metal: ##STR1## (wherein A is a residue forming a heterocyclic ring together with the carbon atom and the nitrogen atom to which it is bonded, X is a residue forming an aromatic group together with the two carbon atoms to which it is bonded, and D is an aromatic residue which may have a substituent, or a heterocyclic amine residue which may have a substituent, and Y is a group having active hydrogen) and an optical recording medium having a recording layer provided on a substrate so that information can be written in and/or read out by a laser, wherein the recording layer contains a metal chelate compound of the dis-azo compound represented by the above formula (I), with a metal.

TECHNICAL FIELD

The present invention relates to a novel metal chelate compound of adis-azo compound with a metal salt, and an optical recording mediumemploying it.

BACKGROUND TECHNIQUE

Optical recording employing a laser makes the storage of high densityinformation recording and its reproduction possible. Accordingly, itsdevelopment has been remarkably proceeded in recent years.

As an example of an optical recording medium, an optical disc may bementioned. In general, an optical disc is designed so that high densityinformation recording is conducted by irradiating a laser beam focusedto about 1 μm to a thin recording layer provided on a disc-shapesubstrate. The recording is conducted in such a manner that uponabsorption of the irradiated laser beam energy, such a portion of therecording layer undergoes a thermal deformation such as decomposition,evaporation or dissolution. Further, the reproduction of the recordinginformation is conducted by reading the difference in reflectancebetween the portion where a deformation was formed by the laser beam anda portion where no such deformation was formed.

Accordingly, the recording layer is required to efficiently absorb thelaser beam energy, and a laser-absorbing dye is employed.

Various constructions have been known for optical recording media ofthis type. For example, Japanese Unexamined Patent Publication No.97033/1980 discloses a medium having a single layer of phthalocyaninetype dye provided on a substrate. However, the phthalocyanine type dyehas a problem that the sensitivity is low, and the decomposition pointis high and vapor deposition is difficult. Further, it has an additionalproblem such that the solubility in an organic solvent is very poor,whereby it can not be used for coating in the form of a coatingsolution.

On the other hand, Japanese Unexamined Patent Publications No.112790/1983, No. 114989/1983, No. 85791/1984 and No. 83236/1985 disclosemedia having cyanine-type dyes as the respective recording layers. Suchdyes have high solubility and thus have a merit that coating in the formof a coating solution is possible. However, they also have a problemthat they are inferior in the light resistance. In this connection,Japanese Unexamined Patent Publication No. 55795/1984 proposes toimprove the light resistance by an addition of a quencher to such acyanine type dye. However, such a proposal is still at an inadequatelevel.

In connection with such problems, Japanese Unexamined Patent PublicationNo. 30090/1987 discloses a recording medium wherein a complex of amonoazo compound with a metal, is employed, as a recording medium havingthe solubility in an organic solvent and the light resistance improved.However, such a compound is inferior in the sensitivity with the lightsensitive wavelength being short, and further it is inferior in thestorage stability at a high temperature high humidity condition, wherebyit has problems as an optical recording medium.

DISCLOSURE OF THE INVENTION

The present invention relates to a metal chelate compound of a dis-azocompound represented by the following formula (I) with a metal: ##STR2##(wherein A is a residue forming a heterocyclic ring together with thecarbon atom and the nitrogen atom to which it is bonded, X is a residueforming an aromatic group together with the two carbon atoms to which itis bonded, D is an aromatic residue which may have a substituent, or aheterocyclic amine residue which may have a substituent, and Y is agroup having active hydrogen), and an optical recording medium employingsuch a metal chelate compound.

Now, the present invention will be described in detail.

In the formula (I), A is a residue forming a heterocyclic ring togetherwith the carbon atom and the nitrogen atom to which it is bonded, and##STR3## includes, for example, the following: ##STR4##

In the above formulas, ring B may be substituted by a C₁₋₆ alkyl groupsuch as a methyl group, an ethyl group, a n-propyl group, an isopropylgroup, a n-butyl group, a tert-butyl group, a sec-butyl group, an-pentyl group, or a n-hexyl group; a C₁₋₆ alkoxy group such as amethoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group,a n-butoxy group, a tert-butoxy group, a sec-butoxy group, a n-pentyloxygroup, or a n-hexyloxy group; or a halogen atom such as a fluorine atom,a chlorine atom, or a bromine atom, R³ is a hydrogen atom; a C₁₋₆ alkylgroup such as a methyl group, an ethyl group, a n-propyl group, anisopropyl group, a n-butyl group, a tert-butyl group, a sec-butyl group,a n-pentyl group, or n-hexyl group; a C₁₋₆ alkoxy group such as amethoxy group, an ethoxy group, a n propoxy group, an isopropoxy group,a n butoxy group, a tert-butoxy group, a sec-butoxy group, a n-pentyloxygroup, or a n-hexyloxy group; a halogen atom such as a fluorine atom, achlorine atom, or a bromine atom; or a C₆₋₁₂ aryl group such as a phenylgroup, a tolyl group, a xylyl group, or a naphthyl group, and R¹⁵ is aC₁₋₆ alkyl group such as a methyl group, an ethyl group, a n-propylgroup, an isopropyl group, a n-butyl group, a tert-butyl group, asec-butyl group, a n-pentyl group, or a n-hexyl group.

In the formula (I), X is a residue forming an aromatic ring such as abenzene ring or a naphthalene ring together with the two carbon atoms towhich it is bonded. Further, X may have at least one substitutedselected from the group consisting of --NR¹ R² (wherein each of R¹ andR² which are independent from each other, is a hydrogen atom; a C₁₋₂₀alkyl group such as a methyl group, an ethyl group, a n-propyl group, anisopropyl group, a n-butyl group, a tert-butyl group, a sec-butyl group,a n pentyl group, a n-hexyl group, a n-heptyl group, a n-octyl group, an-decyl group, n-dodecyl group, or a n-octadecyl group; a C₆₋₁₂ arylgroup such as a phenyl group, a tolyl group, a xylyl group, or anaphthyl group; a C₂₋₁₀ alkenyl group such as a vinyl group, a1-propenyl group, a allyl group, an isopropenyl group, a 1-butenylgroup, a 1,3-butadienyl group, or a 2-pentenyl group; or a C₃₋₁₀cycloalkyl group such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, acycloheptyl group, or a cyclooctyl group, such a C₁₋₂₀ alkyl group, aC₆₋₁₂ aryl group, a C₂₋₁₀ alkenyl group and a C₃₋₁₀ cycloalkyl group maybe substituted by e.g. a C₁₋₁₀ alkoxy group such as a methoxy group, anethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group,a tert-butoxy group, a sec-butoxy group, a n-pentyloxy group, an-hexyloxy group, a n-heptyloxy group, a n-octyloxy group, or an-decyloxy group; a C₂₋₁₂ alkoxyalkoxy group such as methoxymethoxygroup, an ethoxymethoxy group, a propoxymethoxy group, a methoxyethoxygroup, an ethoxyethoxy group, a propoxyethoxy group, a methoxypropoxygroup, an ethoxypropoxy group, a mothoxybutoxy group, or anethoxybutoxyl group; a C₃₋₁₅ alkoxyalkoxyalkoxy group such as amethoxymethoxymethoxy group, a methoxymethoxyethoxy group, amethoxyethoxymethoxy group, a methoxyethoxyethoxy group, anethoxymethoxymethoxy group, an ethoxymethoxyethoxy group, anethoxyethoxymethoxy group, or ethoxyethoxyethoxy group; an allyoxygroup; a C₆₋₁₂ aryl group such as a phenyl group, a polyl group, a xylylgroup, or a naphthyl group; a C₆₋₁₂ aryloxy group such as a phenoxygroup, a tolyloxy group, a xylyloxy group, or a naphthyloxy group; acyano group; a nitro group; a hydroxyl group; a tetrahydrofuryl group; aC₁₋₆ alkylsulfonylamino group such as a methylsulfonylamino group, anethylsulfonylamino group, a n-propylsulfonylamino group, anisopropylsulfonylamino group, a n-butylsulfonylamino group, atert-butylsulfonylamino group, a sec-butylsulfonylamino group, an-pentylsulfonylamino group, or a n-hexylsulfonylamino group; a halogenatom such as a fluorine atom, a chlorine atom, or a bromine atom; a C₂₋₇alkoxycarbonyl group such as a methoxycarbonyl group, an ethoxycarbonylgroup, a n-propoxycarbonyl group, an isopropoxycarbonyl group, an-butoxycarbonyl group, a tert-butoxycarbonyl group, asec-butoxycarbonyl group, a n-pentyloxycarbonyl group, or an-hexyloxycarbonyl group; a C₂₋₇ alkylcarbonyloxy group such as amethylcarbonyloxy group, an ethylcarbonyloxy group, an-propylcarbonyloxy group, an isopropylcarbonyloxy group, an-butylcarbonyloxy group, a tert-butylcarbonyloxy group, asec-butylcarbonyloxy group, a n-pentylcarbonyloxy group, or an-hexylcarbonyloxy group; or a C₂₋₇ alkoxycarbonyloxy group such as amethoxycarbonyloxy group, an ethoxycarbonyloxy group, an-propoxycarbonyloxy group, an isopropoxycarbonyloxy group, an-butoxycarbonyloxyl group, a tert-butoxycarbonyloxy group, asec-butoxycarbonyloxy group, a n-pentyloxycarbonyloxy group, or an-hexyloxycarbonyloxy group, further the C₆₋₁₂ aryl group and the C₃₋₁₀cycloalkyl group represented by R¹ and R² may be substituted by a C₁₋₆alkyl group such as a methyl group, an ethyl group, an n-propyl group,an isopropyl group, a n-butyl group, a tert-butyl group, a sec-butylgroup, a n-pentyl group, or a n-hexyl group); a C₁₋₆ alkyl group such asa methyl group, an ethyl group, a n-propyl group, an isopropyl group, an-butyl group, a tert-butyl group, a sec-butyl group, a n-pentyl group,or a n-hexyl group; a C₁₋₆ alkoxy group such as a methoxy group, anethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group,a tert-butoxy group, a sec-butoxy group, a n-hexyloxy group; and ahalogen atom such as a fluorine atom, a chlorine atom, or a bromineatom.

In the formula (I), D may be an aromatic or heterocyclic amine residuewhich may be substituted, such as: ##STR5## In the above formulas, thesubstituent on ring E, or each of substituents R⁴, R⁵, R⁶, R⁷, R⁸, R⁹and R¹⁰, may be a C₁₋₂₀ alkyl group such as a methyl group, an ethylgroup, a n-propyl group, an isopropyl group, a n-butyl group, atert-butyl group, a sec-butyl group, a n-pentyl group, a n-hexyl group,a n-heptyl group, a n-octyl group, a n-decyl group, a n-dodecyl group,or a n-octadecyl group; a C₃₋₁₀ cycloalkyl group such as a cyclopropylgroup, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, or a cyclobutyl group, which may be substituted bysuch a C₁₋₂₀ alkyl group; a C₁₋₂₀ alkoxy group such as a methoxy group,an ethoxyl group, a n-propoxy group, an isopropoxy group, a n-butoxygroup, a tert-butoxy group, a sec-butoxy group, a n-pentyloxy group, an-hexyloxy group, a n-heptyloxy group, a n-octyloxy group, a n-decyloxygroup, a n-dodecyloxy group, or a n-octadecyloxy group; a nitro group; acyano group; --COOR¹⁷ (wherein R¹⁷ is the above-mentioned C₁₋₂₀ alkylgroup; the above-mentioned C₃₋₁₀ cycloalkyl group which may have a C₁₋₂₀alkyl group; or a phenyl group which may have at least one substituentselected from the group consisting of the above mentioned C₁₋₂₀ alkylgroup, the above mentioned C₃₋₁₀ cycloalkyl group which may besubstituted by a C₁₋₂₀ alkyl group, and the above mentioned C₁₋₂₀ alkoxygroup); a phenyl group which may be substituted by the above-mentionedC₁₋₂₀ alkyl group or the above mentioned C₁₋₂₀ alkoxy group; a C₁₋₂₀alkylsulfonyl group such as a methylsulfonyl group, an ethylsulfonylgroup, a n-propylsulfonyl group, an isopropylsulfonyl group, an-butylsulfonyl group, a tert-butylsulfonyl group, a sec-butylsulfonylgroup, a n-pentylsulfonyl group, a n-hexylsulfonyl group, an-heptylsulfonyl group, a n-octylsulfonyl group, or a n-decylsulfonylgroup; a halogen atom such as a fluorine atom, a chlorine atom, or abromine atom; or a C₁₋₃ perfluoroalkyl group such as a trifluoromethylgroup. n is 1 or 2. Each of Substituents R¹¹, R¹², R¹³ and R¹⁴, may bean allyl group; a C₁₋₈ alkyl group such as a methyl group, an ethylgroup, a n-propyl group, an isopropyl group, a n-butyl group, atert-butyl group, a sec-butyl group, a n-pentyl group, a n-hexyl group,a n-heptyl group, or a n-octyl group; a C₃₋₈ alkoxyalkyl group such as amethoxyethyl group, a methoxypropyl group, a methoxybutyl group, anethoxymethyl group, an ethoxyethyl group, an ethoxypropyl group, anethoxybutyl group, a propoxymethyl group, a propoxyethyl group, apropoxypropyl group, a propoxybutyl group, a butoxymethyl group, or abutoxyethyl group; a C₇₋₁₃ aralkyl group such as a benzyl group, aphenetyl group, a phenylpropyl group, or a naphthylmethyl group; a C₁₋₁₀hydroxyalkyl group such as a hydroxymethyl group, a hydroxyethyl group,a hydroxypropyl group, a hydroxybutyl group, a hydroxypentyl group, or ahydroxyhexyl group; or a C₁₋₁₃ perfluoroalkyl group such as atrifluoromethyl group, and m is 0, 1 or 2.

In the formula (I), Y may be a group having active hydrogen, such as--OH, --SH, --COOH, --SO₂ H, --SO₃ H, --NH₂, --NHR¹⁶, --B(OH)₂,--PO(OH)₂, --NHCOR¹⁶, --NHSO₂ R¹⁶.

In the above formulas R¹⁶ is a C₁₋₆ alkyl group such as a methyl group,an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, atert-butyl group, a sec-butyl group, a n-pentyl group, or a n-hexylgroup; a C₁₋₆ alkoxy group such as a methoxy group, an ethoxy group, a npropoxy group, an isopropoxy group, a n-butoxy group, a tert-butoxygroup, a sec-butoxy group, a n-pentyloxy group, or a n-hexyloxy group; aphenyl group which may be substituted by a halogen atom such as afluorine atom, a chlorine atom or a bromine atom; or a C₁₋₆ alkyl groupsuch as a methyl group, an ethyl group, a n-propyl group, an isopropylgroup, a n-butyl group, a tert-butyl group, a sec-butyl group, an-pentyl group, or a n-hexyl group, which may be substituted by ahalogen atom such as a fluorine atom, a chlorine atom, or a bromineatom.

In a case where Y is an anion-dissociable group such as --OH, --COOH,--SO₃ H, such a compound may be used in that form or in the form of asalt with a cation, for the formation of a metal chelate compound. Assuch a cation, an inorganic cation such as Na+, Li+, or K+, or anorganic cation such as ##STR6## may be mentioned.

As one embodiment of a compound preferred in the present invention, ametal chelate compound of a dis-azo compound represented by thefollowing formula (II): ##STR7## (wherein D and X are as defined above,ring B may have a substituent, and Y' is --COOH, or --SO₃ H), with ametal, may be mentioned.

The substituent on ring B in the above formula (II), may, for example,be the above-mentioned C₁₋₂₀ alkyl group, the above-mentioned C₁₋₂₀alkoxy group, or the above mentioned halogen atom.

Among the compounds represented by the above formula (II), preferred isa metal chelate compound of a dis-azo compound represented by thefollowing formula (III): ##STR8## (wherein D, B, Y', R¹ and R² are asdefined above, and ring C may have a substituent), with a metal, andmore preferred is a metal chelate compound of a dis-azo compoundrepresented by the following formula (IV): ##STR9## (wherein B, C, E,Y', R¹ and R² are as defined above), with a metal.

The substituent on ring C may be the same substituent as the one on ringB.

Further, another embodiment of a compound preferred in the presentinvention is a metal chelate compound of a dis-azo compound representedby the following formula (V): ##STR10## (wherein D, X, Y and R³ are asdefined above), with a metal.

Among the compounds represented by the above formula (V), preferred is ametal chelate compound of a dis-azo compound represented by thefollowing formula (VI): ##STR11## (wherein D, C, R¹, R² and R³ are asdefined above), with a metal, and more preferred is a metal chelatecompound of a dis-azo compound represented by the following formula(VII): ##STR12## (wherein C, E, R¹, R² and R³ are as defined above),with a metal.

In the present invention, the metal to form a chelate with the dis-azocompound is not particularly limited so long as it is a metal capable offorming a metal chelate compound with the dis-azo compound concerned.However, a transition element such as Ni Co, Fe, Ru, Rh, Pd, Os, Ir, orPt, is preferred. Particularly preferred is Ni or Co.

In the present invention, specific examples of the dis-azo compound toform a chelate with a metal, include the following: ##STR13##

Now, a method for producing the metal chelate compound of a dis-azocompound of the present invention will be described.

The metal chelate compound of a dis-azo compound of the presentinvention may be prepared, for example, in accordance with thedisclosure by Furukawa in Analytica Chimica Acta 140 (1982) 281-289.Namely, an amino compound represented by the formula (VIII) or theformula (IX): ##STR14## (wherein D, ring B and R³ are as defined above)is diazotized in accordance with a conventional method, followed bycoupling with a substituted aniline derivative represented by thefollowing formula (X): ##STR15## (wherein C, Y', R¹ and R² are asdefined above) to obtain a dis-azo compound of the above formula (III)or (VI). Then, the above dis-azo compound and a metal salt are reactedin water and/or an organic solvent such as a dioxane, tetrahydrofurnan,acetone or ethanol to produce a metal chelate compound of the presentinvention.

As the anion of the metal salt to be used for the preparation of themetal chelate compound, a monovalent or bivalent anion such as SCN⁻,SbF₆ ⁻, Cl⁻, Br⁻, F⁻, ClO₄ ⁻, BF₄ ⁻, PF₆ ⁻, CH₃ COO⁻, TiF₆ ²⁻, SiF₆ ²⁻,ZrF₆ ²⁻, ##STR16## is preferred. Particularly preferred is BR₄ ⁻, PF₆ ⁻,or CO₃ COO⁻.

Now, the optical recording medium of the present invention will bedescribed.

The optical recording medium of the present invention consistsessentially of a substrate and a recording layer containing the abovemetal chelate compound of a dis-azo compound. However, if necessary, anundercoating layer may be provided on the substrate. Further, as apreferred layer structure, a metal reflective layer of e.g. gold oraluminum, and a protective layer may be formed on the recording layer toobtain a medium having a high reflectance and to obtain a writable CDmedium.

The substrate in the present invention may be transparent or opaque tothe laser beam to be used. As the material for the substrate, a usualsupport for the recording material such as glass, plastic, paper, or aplate-like or foil-like metal, may be mentioned. However, plastics arepreferably used from various reasons. Such plastics include, forexample, acryl resin, methacryl resin, vinylacetate resin, vinylchloride resin, nitrocellulose, polyethylene resin, polypropylene resin,polycarbonate resin, polyimide resin, epoxy resin, and polysulfoneresin. However, from the viewpoint of the productivity, cost andmoisture resistance, a polycarbonate resin substrate of injectionmolding type is used particularly preferably.

The recording layer containing the chelate compound of the dis-azocompound with a metal in the optical medium of the present invention,preferably has a thickness of from 100 Å to 5 μm, more preferably from1,000 Å to 3 μm. With respect to the layer-forming method, a layer maybe formed by a conventional thin layer-forming method such as a vacuumdeposition method, a sputtering method, a doctor blade method, a castingmethod, a spinning method or a dipping method. The spinning method ispreferred from the viewpoint of the mass productivity and the cost.

Further, a binder may be used as the case requires. As the binder, aconventional binder such as polyvinyl alcohol, polyvinylpyrrolidone,ketone resin, nitrocellulose, cellulose acetate, polyvinylbutyral, orpolycarbonate, may be employed. In the case of layer-forming by aspinning method, the rotational speed is preferably from 500 to 5,000rpm. After the spin coating, treatment such as heating or application ofa solvent vapor may be conducted as the case requires.

For improvement of the stability and the light resistance of therecording layer, a transition metal chelate compound (such asacetylacetonate chelate, bisphenyldithiol, salithylaldehydeoxime or abisdithio-α-diketone) may be incorporated as a singlet state oxygenquencher. Furthermore, a homologous dye, or a dye in a differentcategory, such as a triallylmethane type dye, an azo dye, a cyanine typedye, a squallilium type dye, a metal chelate compound of a monoazocompound, or a nickel-indoaniline type dye, may be used in combination.

In a case of forming a recording layer by a doctor blade method, acasting method, a spinning method or a dipping method, particularly by acoating method such as a spinning method, as the coating solvent, asolvent having a boiling pint of from 120 to 160° C., such astetrafluoropropanol, octafluoropentanol, tetrachloroethane, bromoform,dibromoethane, diacetone alcohol, ethylcellosolve, xylene,3-hydro-3-methyl-2-butanone, chlorobenzene, cyclohexanone, or methyllactate, may suitable by used.

Among them, a ketone alcohol type solvent such as diacetone alcohol, or3-hydroxy-3-methyl-2-butanone; a cellosolve type solvent such asmethylcellosolve, or ethylcellosolve; a perfluoroalkyl alcohol typesolvent such as tetrafluoropropanol, or octafluoropentanol; or ahydroxyester type solvent such as methyl lactate, or methyl isobutyrate,may be mentioned as a solvent particularly useful for an injection typepolycarbonate resin substrate which is excellent in the productivity,cost and moisture resistance, without damaging the substrate.

The recording layer of the optical recording medium of the presentinvention may be provided on each side of the substrate or may beprovided on one side only.

Recording on the recording medium thus obtained, is conducted byirradiating a laser beam, preferably a semiconductor laser beam, focusedto a size of 1 μm on the recording layer provided on each side or oneside of the substrate. At the portion irradiated with the laser beam, athermal deformation of the recording layer, such as decomposition,evaporation or melting, takes place due to absorption of the laserenergy. Accordingly, reproduction of the recorded information can beconducted by reading the difference in reflectance between the portionwhere a thermal deformation has taken place by the laser beam and theportion where no such deformation has taken place.

As the laser beam to be used for recording and reproduction of theoptical recording medium of the present invention, a N₂, He-Cd, Ar,He-Ne, rubie, semiconductor or dye laser may be mentioned. However, fromthe viewpoint of the light weight, easy handing and compactness, asemiconductor laser is preferably employed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a drawing showing a visible range absorption spectrum of thenickel chelate compound of Example 1, wherein the ordinate representsabsorbance, and the abscissa represents wavelength (nm).

FIG. 2 is a drawing showing an infrared absorption spectrum of thenickel chelate compound of Example 1.

FIG. 3 is a drawing showing an absorption spectrum of the coating layerof Example 1, wherein the ordinate represents absorbance, and theabscissa represents wavelength (nm).

FIG. 4 is a drawing showing an infrared absorption spectrum of thenickel chelate compound obtained in Example 2.

FIG. 5 is a drawing showing an infrared absorption spectrum of thenickel chelate compound obtained in Example 3.

FIG. 5 is a drawing showing a visible range absorption spectrum of thenickel chelate compound obtained in Example 4.

FIG. 7 is a drawing showing an infrared absorption spectrum of a nickelchelate compound obtained in Example 4.

FIG. 8 is a drawing showing an infrared absorption spectrum of thenickel chelate compound obtained in Example 6.

FIG. 9 is a drawing showing an infrared absorption spectrum of thenickel chelate compound obtained in Example 9.

FIG. 10 is a drawing showing a visible range absorption spectrum of thenickel chelate compound obtained in Example 13.

FIG. 11 is a drawing showing an infrared absorption spectrum of thenickel chelate compound obtained in Example 13.

FIG. 12 is a drawing showing an absorption spectrum of the coating layerof Example 13.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the present invention will be described in more detail withreference to Examples. However, such Examples by no means restrict thepresent invention.

EXAMPLE 1 (a) Preparation of a Compound

2.5 g of 2-amino-6-phenylbenzothiazole represented by the followingstructural formula: ##STR17## was dissolved in a mixture solutioncomprising 15 ml of phospholic acid, 15 ml of acetic acid and 5 ml ofpropionic acid and diazotized at from 0 to -3° C. by means of 3.4 g of45% nitrosylsulfuric acid.

To a solution having 1.65 g of 3-dimethylaminobenzoic acid dissolved in100 ml of methanol, the diazotized solution thus obtained was dropwiseadded at a temperature of from 0 to 5° C., followed by neutralization bymeans of an alkali compound such as sodium acetate or aqueous ammonia.Obtained crystals were collected by filtration and dried to obtain 2.5 gof brown crystals represented by the following structural formula. Themaximum absorption wavelength (in chloroform) of this compound was 595nm. ##STR18##

0.8 g of the dis-azo compound thus obtained was dissolved in 50 ml oftetrahydrofuran, and 2.6 g of 40% nickel borofluoride was added,followed by filtration. The filtrate was poured into a solution having50 g of sodium borofluoride dissolved in 50 ml of water, and excesswater was further added to precipitate crystals. Obtained crystals werecollected by filtration and dried to obtain 0.5 g of a nickel chelatecompound as black crystals. The maximum absorption wavelength (inchloroform) of this compound was 655 nm (see FIG. 1).

Further, the infrared absorption spectrum of this compound is shown inFIG. 2.

Physical properties

Melting point: at least 250° C.

λmax =655 nm (in chloroform)

ε=12.1×10⁴

(b) Preparation of an Optical Recording Medium

0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a) was dissolved in 7.5 g ofoctafluoropentanol and filtered through a filter of 0.22 μm to obtain asolution. 5 ml of this solution was dropped on a injection moldedpolycarbonate resin substrate having a diameter of 5 inch and providedwith groove having a depth of 700 Å and a width of 0.7 μm and coated bya spinning method at a rotational speed of 500 rpm. After the coating,the coating layer was dried at 60° C. for 10 minutes. The maximumabsorption wavelengths of the coating layer were 635 nm and 691 nm.

FIG. 3 shows the absorption spectrum of the coating layer.

Then, on the coating layer, a film of gold was formed in a thickness of2,000 Å by a sputtering method to form a reflective layer. Further, onthis reflective layer, an ultraviolet-curable resin was spin-coated andthen cured by irradiation with ultraviolet rays to form a protectivelayer having a thickness of 10 μm to obtain an optical recording medium.

(c) Optical Recording

While rotating the above recording medium at a speed of 1.2 m/s, asemiconductor laser beam having a center wavelength of 780 nm wasirradiated with a recording power of 7.0 mW to record EFM signals. Then,this recorded portion was reproduced by a CD layer with a semiconductorlaser having a center wavelength of 780 nm, whereby excellentreproduction signals were obtained.

Further, tests for light resistance (Xenone Fade Meter Accelerated Test;60 hours) and storage stability (70° C, 85% RH; 500 hours) wereconducted, whereby no deterioration in the sensitivity and reproductionsignals was observed as compared with the initial values, and the mediumwas found to be excellent as an optical recording medium.

COMPARATIVE EXAMPLE 1

An optical recording medium was prepared in the same manner as inExample 1 except that a nickel complex obtained from a monoazo compoundrepresented by the following structural formula: ##STR19## and nickelborofluoride, was employed.

The sensitivity and the storage stability were evaluated and compared,whereby both the sensitivity and the storage stability were inferior ascompared with the optical recording medium of Example 1 of the presentinvention.

EXAMPLE 2 (a) Preparation of a Compound

0.3 g of a dis-azo compound represented by the following structuralformula: ##STR20## was dissolved in a mixture solution comprising 30 mlof tetrahydrofuran and 30 ml of water, and 0.080 g of nickel acetate wasadded thereto, followed by stirring at room temperature. After addingexcess water, precipitated crystals were collected by filtration, washedwith methanol and toluene and dried to obtain 0.148 g of a nickelchelate compound as brown crystals. The maximum absorption wavelength(in chloroform) of this product was 673 nm. Further, the infraredabsorption spectrum of this compound is shown in FIG. 4.

Physical properties

Melting point: at least 250° C.

λmax=673 nm (in chloroform)

ε=9.7×10⁴

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a) was employed. The maximumabsorption wavelengths of the coating layer were 652 nm and 705 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

While rotating the above recording medium at a speed of 1.2 m/s, asemiconductor laser beam having a center wavelength of 780 nm wasirradiated with a recording power of 6.8 mW to record EFM signals. Then,this recorded portion was reproduced by a CD player with a semiconductorlaser having a center wavelength of 780 nm, whereby excellentreproduction signals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 3 (a) Preparation of a Compound

0.03 g of a dis-azo compound represented by the following structuralformula: ##STR21## was dissolved in a mixture solution comprising 30 mlof tetrahydrofuran and 30 ml of water, and 0.087 g of nickel acetate wasadded thereto, followed by stirring at room temperature. After addingexcess water, precipitated crystals were collected by filtration, washedwith methanol and dried to obtain 0.253 g of a nickel chelate compoundas brown crystals. The maximum absorption wavelength (in chloroform) ofthis compound was 659 nm. Further, the infrared absorption spectrum ofthis compound is shown in FIG. 5.

Physical properties

Melting point: 203-204° C. (decomposed)

λmax=659 nm (in chloroform)

ε=7.5×10⁴

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a) was employed. The maximumabsorption wavelengths of the coating layer were 639 nm and 695 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

On the above recording medium, EFM signals were recorded and thenreproduced in the same manner as in Example 1, whereby excellentreproduction signals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 4 (a) Preparation of a Compound

2.54 g of 2-amino-6-phenylazobenzothiazol represented by the followingstructural formula: ##STR22## was dissolved in a mixture solutioncomprising 25 ml of phospholic acid, 35 ml of acetic acid and 12.5 ml ofpropionic acid, and diazotized at a temperature of from 0 to -3° C. bymeans of 3.39 g of 45% nitrosylsulfuric acid. To a solution having 3.14g of sodium 3-diethylaminobenzonesulfonate dissolved in 100 ml ofmethanol, the diazotized solution thus obtained was dropwise added at atemperature of from 0 to 5° C., followed by neutralization by means ofan alkali compound such as sodium acetate or aqueous ammonia. Obtainedcrystals were collected by filtration and dried to obtain 1.84 g ofblackish purple crystals represented by the following structuralformula. Further, the maximum absorption wavelength (in chloroform) ofthis compound was 566 nm. ##STR23## 0.5 g of the dis-azo compound thusobtained and 0.08 g of sodium acetate were dissolved in a mixturesolution comprising 30 ml of tetrahydrofuran and 30 ml of water, and0.14 g of nickel acetate was added thereto, followed by stirring at roomtemperature for 20 hours. The solution was added to 300 ml of water.Precipitated crystals were collected by filtration, washed with methanoland water and dried to obtain 0.22 g of a nickel chelate compound asgreenish brown crystals. The maximum absorption wavelength (inchloroform) of this product was 665 nm.

Further, the infrared absorption spectrum of this compound is shown inFIG. 6.

Physical properties

Melting point: at least 250° C.

λmax=665 nm (in chloroform)

ε=1.30×10⁵

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a), was employed. The maximumabsorption wavelengths of the coating layer were 649 nm and 706 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

On the above recording medium, EFM signals were recorded and thenreproduced in the same manner as in Example 1, whereby excellentreproduction signals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 5 (a) Preparation of a Compound

0.5 g of the dis-azo compound prepared in Example 4 and 0.08 g of sodiumacetate were dissolved in a mixture solution comprising 30 ml oftetrahydrofuran and 30 ml of water, and 0.15 g of cobalt acetate wasadded thereto, followed by stirring at room temperature for 20 hours.The solution was added to 300 ml of water. Then, precipitated crystalswere collected by filtration, washed with methanol and water and driedto obtain 0.15 g of a cobalt chelate compound as brown crystals. Themaximum absorption wavelength (in chloroform) of this compound was 658nm.

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with cobalt,obtained in the above Preparation Example (a), was employed. The maximumabsorption wavelengths of the coating layer were 643 nm and 699 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

On the above recording medium, EFM signals were recorded and reproducedin the same manner as in Example 1, whereby excellent reproductionsignals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 6 (a) Preparation of a Compound

0.8 g of a dis-azo compound represented by the following structuralformula: ##STR24## and 0.14 g of sodium acetate were dissolved in amixture solution comprising 20 ml of tetrahydrofuran and 20 ml of water,and 0.26 g nickel acetate was added thereto, followed by stirring atroom temperature for 2 hours. Precipitated crystals were collected byfiltration, washed with methanol and toluene and dried to obtain 0.34 gof a nickel chelate compound as brown crystals. The maximum absorptionwavelength (in chloroform) of this compound was 658 nm. The infraredabsorption spectrum of this compound is shown in FIG. 8.

Physical properties

Melting point: 250° C.

λmax=658 nm (in chloroform)

ε=6.7×10⁴

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a), was employed. The maximumabsorption wavelengths of the coating layer were 650 nm and 713 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

On the above recording medium, EFM signals were recorded and reproducedin the same manner as in Example 1, whereby excellent reproductionsignals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 7 (a) Preparation of a Compound

0.66 g of a dis-azo compound represented by the following structuralformula: ##STR25## was dissolved in 35 ml of methanol, and 0.17 g ofnickel acetate was added thereto, followed by stirring at roomtemperature for 5 hours. Precipitated crystals were collected byfiltration, washed with methanol and dried to obtain 0.010 g of a nickelchelate compound as brown crystals. The maximum absorption wavelength(in chloroform) of this compound was 659 nm.

Physical properties

Melting point: at least 250° C.

λmax=659 nm (in chloroform)

ε=1.25×10⁵

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a), was employed. The maximumabsorption wavelengths of this coating layer were 643 nm and 704 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

On the above recording medium, EFM signals were recorded and reproducedin the same manner as in Example 1, whereby excellent reproductionsignals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 8 (a) Preparation of a Compound

0.66 g of the dis-azo compound used in the above Example 7 was dissolvedin 35 ml of methanol, and 0.17 g of cobalt acetate was added thereto,followed by stirring at room temperature for 5 hours. Precipitatedcrystals were collected by filtration, washed with methanol and dried toobtain 0.14 g of a cobalt chelate compound as brown crystals. Themaximum absorption wavelength (in chloroform) of this compound was 652nm.

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the cobalt chelate compound of a dis-azo compound,obtained in the above Preparation Example (a), was employed. The maximumabsorption wavelengths of the coating layer were 643 nm and 692 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

On the above recording medium, EFM signals were recorded and reproducedin the same manner as in Example 1, whereby excellent reproductionsignals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 9 (a) Preparation of a Compound

0.3 g of a dis-azo compound represented by the following structuralformula: ##STR26## and 0.048 g of sodium acetate were dissolved in 30 mlof tetrahydrofuran and 30 ml of water, and 0.087 g nickel acetate wasadded thereto, followed by stirring at room temperature for 20 hours.Precipitated crystals were collected by filtration, washed withmethanol, water and toluene and dried to obtain 0.16 g of a nickelchelate compound as brown crystals. The maximum absorption wavelength(in chloroform) of this compound was 665 nm. The infrared absorptionspectrum of this compound is shown in FIG. 9.

Physical properties

Melting point: at least 250° C.

λmax=665 nm (in chloroform)

ε=1.19×10⁵

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a), was employed. The maximumabsorption wavelengths of the coating layer were 646 nm and 714 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

On the above recording medium, EFM signals were recorded and reproducedin the same manner as in Example 1, whereby excellent reproductionsignals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 10 (a) Preparation of a Compound

0.8 g of a dis-azo compound represented by the following structuralformula: ##STR27## was dissolved in 50 ml of dioxane, and 2.6 g of 40%nickel borofluoride was added thereto, followed by filtration. Thefiltrate was poured into a solution having 50 g of NH₄ PF₆ dissolved in50 ml of water, and excess water was added to precipitate crystals. Theobtained crystals were collected by filtration, and dried to obtain 0.55g of a nickel chelate compound as black crystals. The maximum absorptionwavelength (in chloroform) of this compound was 646 nm.

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a), was dissolved in 5 g oftetrafluoropropanol. The maximum absorption wavelengths of this coatinglayer were 626 nm and 682 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

On the above recording medium, EFM signals were recorded and reproducedin the same manner as in Example 1, whereby excellent reproductionsignals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 11 (a) Preparation Example

A dis-azo compound represented by the following structural formula:##STR28## was dissolved in 50 ml of acetone, and 2.6 g of 40% nickelborofluoride was added thereto, followed by filtration. The filtrate waspoured into a solution having 50 g of sodium borofluoride dissolved in50 ml of water, and excess water was further added to precipitatecrystals. The obtained crystals were collected by filtration and driedto obtain 0.5 g of a nickel chelate compound as black crystals. Themaximum absorption wavelength (in chloroform) of this compound was 640nm.

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the nickel chelate compound of a dis-azo compound,obtained in the above Preparation Example (a), was dissolved in 5 g ofdiacetone alcohol. The maximum absorption wavelengths of the coatinglayer were 621 nm and 678 nm.

(c) Optical Recording

While rotating the above recording medium at a speed of 4 m/s, a He-Nelaser beam of about 1 μm having a center wavelength of 633 nm wasirradiated with a recording power of 6.0 mW, whereby a pit having clearoutline was formed.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 12

Compounds as identified in Tables 1 and 2 were prepared in accordancewith the methods disclosed in Examples 1 to 11, and chelate compoundswith metals were obtained. Then, solutions prepared by using such metalchelate compounds were coated on substrates to obtain optical recordingmedia. Recording was conducted by using a semiconductor laser as a lightsource, whereby every medium had excellent sensitivity and was excellentalso in the light resistance and storage stability.

The maximum wavelengths of the visible range absorption spectra inchloroform of the metal chelate compounds and the maximum absorptionwavelengths of the coating layers formed by using such metal chelatecompounds, are shown in Tables 1 and 2, respectively.

                                      TABLE 1                                     __________________________________________________________________________     ##STR29##                                                                                                                        Maximum absorption        Compound                                       Metal                                                                              wavelength of the         No.   D         R.sup.18                                                                           Y        R.sup.2                                                                             R.sup.1                                                                             R.sup.19                                                                           ion  coating layer             __________________________________________________________________________                                                        (nm)                      12-1                                                                                 ##STR30##                                                                              H    COOH     C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                     H    Ni.sup.2+                                                                          625, 664                  12-2                                                                                 ##STR31##                                                                              H    COOH     C.sub.3 H.sub.7 (n)                                                                 C.sub.3 H.sub.7 (n)                                                                 H    Ni.sup.2+                                                                          628, 667                  12-3                                                                                 ##STR32##                                                                              H    COOH     C.sub.4 H.sub.9 (n)                                                                 C.sub.4 H.sub.9 (n)                                                                 H    Ni.sup.2+                                                                          628, 668                  12-4                                                                                 ##STR33##                                                                              H    COOH     C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                     H    Co.sup.2+                                                                          614, 668                  12-5                                                                                 ##STR34##                                                                              H    COOH     C.sub.3 H.sub.7 (n)                                                                 C.sub.3 H.sub.7 (n)                                                                 H    Co.sup.2+                                                                          615, 669                  12-6                                                                                 ##STR35##                                                                              H    COOH     C.sub.4 H.sub.9 (n)                                                                 C.sub.4 H.sub.9 (n)                                                                 H    Co.sup.2+                                                                          617, 673                  12-7                                                                                 ##STR36##                                                                              H    COOH     CH.sub.3                                                                            CH.sub.3                                                                            H    Co.sup.2+                                                                          608, 659                  12-8                                                                                 ##STR37##                                                                              Cl   COOH     C.sub.4 H.sub.9 (n)                                                                 C.sub.4 H.sub.9 (n)                                                                 H    Ni.sup.2+                                                                          631, 677                  12-9                                                                                 ##STR38##                                                                              CH.sub.3                                                                           COOH     C.sub.4 H.sub.9 (n)                                                                 C.sub.4 H.sub.9 (n)                                                                 H    Ni.sup.2+                                                                          631, 670                  12-10                                                                                ##STR39##                                                                              CH.sub.3                                                                           COOH     C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                     H    Ni.sup.2+                                                                          631, 657                  12-11                                                                                ##STR40##                                                                              CH.sub.3                                                                           COOH     C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                     H    Co.sup.2+                                                                          618, 665                  12-12                                                                                ##STR41##                                                                              H    NHSO.sub.2 C.sub.3 H.sub.7                                                             C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                     H    Ni.sup.2+                                                                          655                       12-13                                                                                ##STR42##                                                                              CH.sub.3                                                                           OOOH     CH.sub.3                                                                            CH.sub.3                                                                            H    Ni.sup.2+                                                                          652                       12-14                                                                                ##STR43##                                                                              H    SO.sub.3 Na                                                                            CH.sub.3                                                                            CH.sub.3                                                                            H    Co.sup.2+                                                                          614, 651                  12-15                                                                                ##STR44##                                                                              H    SO.sub.3 Na                                                                            C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                     OCH.sub.3                                                                          Co.sup.2+                                                                          635,                      __________________________________________________________________________                                                        672                   

                                      TABLE 2                                     __________________________________________________________________________     ##STR45##                                                                                                                        Maximum absorption        Compound                                        Metal                                                                             wavelength of the         No.    D            Y     R.sup.2    R.sup.1    ion coating maser             __________________________________________________________________________                                                        (nm)                      12-16                                                                                 ##STR46##   COOH  C.sub.2 H.sub.4 OCH.sub.3                                                                C.sub.2 H.sub.4 OCH.sub.3                                                                Ni.sup.2+                                                                         626, 683                  12-17                                                                                 ##STR47##   COOH  C.sub.2 H.sub.4 OC.sub.2 H.sub.4 OCH.sub.3                                               C.sub.2 H.sub.4 OC.sub.2 H.sub.4                                              OCH.sub.3  Ni.sup.2+                                                                         626, 684                  12-18                                                                                 ##STR48##   COOH  C.sub.2 H.sub.4 OC.sub.3 H.sub.7 (i)                                                     C.sub.2 H.sub.4 OC.sub.3 H.sub.7                                                         Ni.sup.2+                                                                         626, 682                  12-19                                                                                 ##STR49##   COOH  CH.sub.2 COOCH.sub.3                                                                     CH.sub.2 COOCH.sub.3                                                                     Ni.sup.2+                                                                         621, 678                  12-20                                                                                 ##STR50##   COOH  C.sub.2 H.sub.5                                                                          CH.sub.2 COOC.sub.2 H.sub.5                                                              Ni.sup.2+                                                                         627, 685                  12-21                                                                                 ##STR51##   COOH  C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                         Ni.sup.2+                                                                         628, 687                  12-22                                                                                 ##STR52##   COOH  C.sub.2 H.sub.4 OCOCH.sub.3                                                              C.sub.2 H.sub.4 OCOCH.sub.3                                                              Ni.sup.2+                                                                         627, 684                  12-23                                                                                 ##STR53##   COOH  C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                          Ni.sup.2+                                                                         627, 686                  12-24                                                                                 ##STR54##   COOH  C.sub.2 H.sub.4 OCOC.sub.2 H.sub.5                                                       C.sub.2 H.sub.4 OCOC.sub.2 H.sub.5                                                       Ni.sup.2+                                                                         627, 683                  12-25                                                                                 ##STR55##   COOH  CH.sub.3   CH.sub.3   Ni.sup.2+                                                                         638, 695                  12-26                                                                                 ##STR56##   COOH  C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                          Cu.sup.2+                                                                         636, 695                  12-27                                                                                 ##STR57##   COOH  CH.sub.3   CH.sub.3   Zu.sup.2+                                                                         635, 696                  12-28                                                                                 ##STR58##   COOH  CH.sub.3   CH.sub.3   Ni.sup.2+                                                                         637, 695                  12-29                                                                                 ##STR59##   COOH  CH.sub.3   CH.sub.3   Ni.sup.2+                                                                         635, 694                  12-30                                                                                 ##STR60##   COOH  C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                          Ni.sup.2+                                                                         636,                      __________________________________________________________________________                                                        695                   

EXAMPLE 13 (a) Preparation of a Compound

2.18 g of 2-amino 4-methyl-5-phenylthiazole represented by the followingstructural formula: ##STR61## was dissolved in a mixture solutioncomprising 30 ml of phospholic acid, and 60 ml of acetic acid and 5 mlof propionic acid, and diazotized at a temperature of from 0 to -5° C.by means of 3.38 g of 45% nitrosylsulfric acid. To a solution having1.65 g of 3-dimethylaminobenzoic acid dissolved in 100 ml of methanol,the diazotized solution thus obtained was dropwise added at atemperature of from 0 to 5° C., followed by neutralization by means ofan alkali compound such as sodium acetate or aqueous ammonia. Theobtained crystals were collected by filtration and dried to obtain 1.75g of blackish brown crystals represented by the following structuralformula. The maximum wavelength (in chloroform) of this compound was 623nm. ##STR62##

1.0 of the dis-azo compound thus obtained was dissolved in 50 ml oftetrahydrofuran, and 3.6 g of 40% nickel borofluoride was added,followed by filtration. The filtrate was poured into a solution having50 g of sodium borofluoride dissolved in 50 ml of water, and excesswater was further added to precipitate crystals. The crystals thusobtained, were collected by filtration and dried to obtain 0.2 g of anickel chelate compound as black crystals. The maximum absorptionwavelength (in chloroform) of this compound was 650 nm (see FIG. 10).

Further, the infrared absorption spectrum of this compound is shown inFIG. 11.

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a), was employed. The maximumabsorption wavelengths of the coating layer were 660 nm and 715 nm. InFIG. 12, the absorption spectrum of the coating layer is shown.

(c) Optical Recording

While rotating the above optical recording medium at a speed of 1.2 m/s,a semiconductor laser beam having a center wavelength of 780 nm wasirradiated with a recording power of 7.0 mW, whereby a clear pit wasformed.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 14 (a) Preparation of a compound

1.0 g of a dis-azo compound represented by the following structuralformula: ##STR63## was dissolved in 50 ml of dioxane, and 3.6 g of 40%nickel borofluoride was added thereto, followed by filtration. Thefiltrate was poured into a solution having 50 g of NH₄ PF₆ dissolved in500 ml of water, and excess water was further added to precipitatecrystals. The crystals thus obtained, were collected by filtration anddried to obtain 0.35 g of a nickel chelate compound as blackishcrystals. The maximum absorption wavelength (in chloroform) of thiscompound was 642 nm.

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,obtained in the above Preparation Example (a), was dissolved in 5 g oftetrafluoropropanol. The maximum absorption wavelengths of this coatinglayer were 645 nm and 700 nm.

Then, on this coating layer, a reflective layer and a protective layerwere formed in the same manner as in Example 1 to obtain an opticalrecording medium.

(c) Optical Recording

On the above recording medium, EFM signals were recorded and reproducedin the same manner as in Example 1, whereby excellent reproductionsignals were obtained.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 15 (a) Preparation Example

1.0 g of a dis-azo compound represented by the following structuralformula: ##STR64## was dissolved in 50 ml of acetone, and 3.6 g of 40%nickel borofluoride was added thereto, followed by filtration. Thefiltrate was poured into a solution having 50 g of sodium borofluoridedissolved in 50 ml of water, and excess water was further added toprecipitate crystals. The crystals thus obtained were collected byfiltration and dried to obtain 0.3 g of a nickel chelate compound asblack crystals. The maximum absorption wavelength (in chloroform) ofthis compound was 640 nm.

(b) Preparation of an Optical Recording Medium

A coating layer was formed in the same manner as in Example 1 exceptthat 0.15 g of the chelate compound of a dis-azo compound with nickel,prepared in the above Preparation Example (a), was dissolved in 5 g ofdiacetone alcohol and the rotational speed of the spinning method waschanged to 700 rpm. The maximum absorption wavelengths of the coatinglayer were 650 nm and 703 nm.

(c) Optical Recording

While rotating the above recording medium at a speed of 4 m/s in thesame manner as in Example 11, a He-Ne laser beam of about 1 μm having acenter wavelength of 633 nm was irradiated with a recording power of 6.0mW, whereby a pit having a clear outline was formed.

Further, the light resistance and storage stability tests were conductedin the same manner as in Example 1, whereby no deterioration in thesensitivity and reproduction signals was observed as compared with theinitial values, and the medium was found to be excellent as an opticalrecording medium.

EXAMPLE 16

Compounds as identified in Table 3 were prepared in accordance with themethods disclosed in Examples 13 to 15 and chelate compounds with metalswere obtained. Then, solutions prepared by using these metal chelatecompounds were coated on substrates to obtain optical recording media.Recording was conducted by using a semiconductor laser as a lightsource, whereupon every medium had excellent sensitivity and wasexcellent also in the light resistance and storage stability.

The maximum absorption wavelengths of the coating layers employing themetal chelate compounds are shown in Table 3.

Further, in addition to the compounds used in the above Examples,specific examples of the metal chelate compound of a dis-azo compoundwith metal, useful for the optical recording medium of the presentinvention, are as shown in Table 4.

                                      TABLE 3                                     __________________________________________________________________________     ##STR65##                                                                                                                 Maximum absorption               Compound                                 Metal                                                                             wavelength of the                No.   D            R.sup.2    R.sup.1    ion coating laser                    __________________________________________________________________________                                                 (nm)                             16-1                                                                                 ##STR66##   C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                          Ni.sup.2+                                                                         660, 710                         16-2                                                                                 ##STR67##   C.sub.3 H.sub.7 (n)                                                                      C.sub.3 H.sub.7 (n)                                                                      Ni.sup.2+                                                                         655, 707                         16-3                                                                                 ##STR68##   C.sub.4 H.sub.9 (n)                                                                      C.sub.4 H.sub.9 (n)                                                                      Ni.sup.2+                                                                         656, 706                         16-4                                                                                 ##STR69##   C.sub.2 H.sub.4 OCH.sub.3                                                                C.sub.2 H.sub.4 OCH.sub.3                                                                Ni.sup.2+                                                                         648, 699                         16-5                                                                                 ##STR70##   C.sub.2 H.sub.4 OC.sub.2 H.sub.4 OCH.sub.3                                               C.sub.2 H.sub.4 OC.sub.2 H.sub.4 OCH.sub.3                                               Ni.sup.2+                                                                         645, 692                         16-6                                                                                 ##STR71##   C.sub.2 H.sub.4 OC.sub.3 H.sub.7 (i)                                                     C.sub.2 H.sub.4 OC.sub.3 H.sub.7 (i)                                                     Ni.sup.2+                                                                         647, 695                         16-7                                                                                 ##STR72##   CH.sub.2 COOCH.sub.3                                                                     CH.sub.2 COOCH.sub.3                                                                     Ni.sup.2+                                                                         640, 690                         16-8                                                                                 ##STR73##   C.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                         C.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                         Ni.sup.2+                                                                         648, 697                         16-9                                                                                 ##STR74##   C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                         Ni.sup.2+                                                                         650, 700                         16-10                                                                                ##STR75##   C.sub.2 H.sub.4 OCOCH.sub.3                                                              C.sub.2 H.sub.4 OCOCH.sub.3                                                              Ni.sup.2+                                                                         651, 699                         16-11                                                                                ##STR76##   C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.4 OCOCH.sub.3                                                              Ni.sup.2+                                                                         653, 701                         16-12                                                                                ##STR77##   C.sub.2 H.sub.4 OCOOC.sub. 2 H.sub.5                                                     C.sub.2 H.sub.4 OCOOC.sub.2 H.sub.5                                                      Ni.sup.2+                                                                         652, 700                         16-13                                                                                ##STR78##   CH.sub.3   CH.sub.3   Ni.sup.2+                                                                         664, 710                         16-14                                                                                ##STR79##   CH.sub.3   CH.sub.3   Co.sup.2+                                                                         665, 712                         16-15                                                                                ##STR80##   C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                          Cu.sup.2+                                                                         660, 708                         16-16                                                                                ##STR81##   CH.sub.3   CH.sub.3   Zu.sup.2+                                                                         658, 714                         16-17                                                                                ##STR82##   CH.sub.3   CH.sub.3   Ni.sup.2+                                                                         650, 700                         16-18                                                                                ##STR83##   CH.sub.3   CH.sub.3   Ni.sup.2+                                                                         648, 699                         16-19                                                                                ##STR84##   C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                          Ni.sup.2+                                                                         653, 704                         __________________________________________________________________________

                                      TABLE 4                                     __________________________________________________________________________    Disazo compound                          Metal ion                            __________________________________________________________________________     ##STR85##                               Ni.sup.2+                             ##STR86##                               Ni.sup.2+                             ##STR87##                               Ni.sup.2+                             ##STR88##                               Ni.sup.2+                             ##STR89##                               Ni.sup.2+                             ##STR90##                               Ni.sup.2+                             ##STR91##                               Ni.sup.2+                             ##STR92##                               Ni.sup.2+                             ##STR93##                               Ni.sup.2+                             ##STR94##                               Ni.sup.2+                             ##STR95##                               Ni.sup.2+                             ##STR96##                               Ni.sup.2+                             ##STR97##                               Ni.sup.2+                             ##STR98##                               Ni.sup.2+                             ##STR99##                               Ni.sup.2+                             ##STR100##                              Ni.sup.2+                             ##STR101##                              Ni.sup.2+                             ##STR102##                              Ni.sup.2+                             ##STR103##                              Ni.sup.2+                             ##STR104##                              Ni.sup.2+                             ##STR105##                              Ni.sup.2+                             ##STR106##                              Ni.sup.2+                             ##STR107##                              Ni.sup.2+                             ##STR108##                              Ni.sup.2+                             ##STR109##                              Ni.sup.2+                             ##STR110##                              Ni.sup.2+                             ##STR111##                              Ni.sup.2+                             ##STR112##                              Ni.sup.2+                             ##STR113##                              Ni.sup.2+                             ##STR114##                              Ni.sup.2+                             ##STR115##                              Ni.sup.2+                             ##STR116##                              Ni.sup.2+                             ##STR117##                              Ni.sup.2+                             ##STR118##                              Ni.sup.2+                             ##STR119##                              Ni.sup.2+                             ##STR120##                              Ni.sup.2+                             ##STR121##                              Ni.sup.2+                             ##STR122##                              Ni.sup.2+                             ##STR123##                              Ni.sup.2+                             ##STR124##                              Ni.sup.2+                             ##STR125##                              Ni.sup.2+                             ##STR126##                              Ni.sup.2+                             ##STR127##                              Ni.sup.2+                             ##STR128##                              Ni.sup.2+                             ##STR129##                              Ni.sup.2+                             ##STR130##                              Ni.sup.2+                             ##STR131##                              Ni.sup.2+                             ##STR132##                              Ni.sup.2+                             ##STR133##                              Ni.sup.2+                             ##STR134##                              Ni.sup.2+                             ##STR135##                              Ni.sup.2+                             ##STR136##                              Ni.sup.2+                             ##STR137##                              Ni.sup.2+                             ##STR138##                              Ni.sup.2+                             ##STR139##                              Ni.sup.2+                             ##STR140##                              Ni.sup.2+                             ##STR141##                              Ni.sup.2+                             ##STR142##                              Ni.sup.2+                             ##STR143##                              Ni.sup.2+                             ##STR144##                              Ni.sup.2+                             ##STR145##                              Ni.sup.2+                             ##STR146##                              Ni.sup.2+                             ##STR147##                              Ni.sup.2+                             ##STR148##                              Ni.sup.2+                             ##STR149##                              Ni.sup.2+                             ##STR150##                              Ni.sup.2+                             ##STR151##                              Ni.sup.2+                             ##STR152##                              Ni.sup.2+                             ##STR153##                              Ni.sup.2+                             ##STR154##                              Ni.sup.2+                             ##STR155##                              Ni.sup.2+                             ##STR156##                              Ni.sup.2+                             ##STR157##                              Ni.sup.2+                             ##STR158##                              Ni.sup.2+                             ##STR159##                              Ni.sup.2+                             ##STR160##                              Ni.sup.2+                             ##STR161##                              Ni.sup.2+                             ##STR162##                              Ni.sup.2+                             ##STR163##                              Ni.sup.2+                             ##STR164##                              Ni.sup.2+                             ##STR165##                              Ni.sup.2+                             ##STR166##                              Ni.sup.2+                             ##STR167##                              Ni.sup.2+                             ##STR168##                              Ni.sup.2+                             ##STR169##                              Ni.sup.2+                             ##STR170##                              Ni.sup.2+                             ##STR171##                              Ni.sup.2+                             ##STR172##                              Ni.sup.2+                             ##STR173##                              Ni.sup.2+                             ##STR174##                              Ni.sup.2+                             ##STR175##                              Ni.sup.2+                             ##STR176##                              Ni.sup.2+                             ##STR177##                              Ni.sup.2+                             ##STR178##                              Ni.sup.2+                             ##STR179##                              Ni.sup.2+                             ##STR180##                              Ni.sup.2+                             ##STR181##                              Ni.sup.2+                             ##STR182##                              Ni.sup.2+                             ##STR183##                              Ni.sup.2+                            __________________________________________________________________________

We claim:
 1. A metal chelate compound of a dis-azo compound representedby the following formula (I) with a metal: ##STR184## is selected fromthe group consisting of ##STR185## wherein ring B may be substituted bya C₁₋₆ alkyl group, a C₁₋₆ alkoxy group, or a halogen atom, R³ is ahydrogen atom, a C₁₋₆ alkyl group, a C₁₋₆ alkoxy group, a halogen atomor a C₁₋₁₂ aryl group, and R¹⁵ is a hydrogen atom or a C₁₋₆ alkyl group,X is a residue forming an aromatic group together with the two carbonatoms to which it is bonded, D is an aromatic residue which may have asubstituent, or a heterocyclic amine residue which may have asubstituent, and Y is a group having active hydrogen.
 2. The metalchelate compound according to claim 1, wherein the residue X in theformula (I) has at least one substituent selected from the groupconsisting of --NR¹ R² wherein each of R¹ and R² which are independentfrom each other, is a hydrogen atom, a C₁₋₂₀ alkyl group which may havea substituent, a C₁₋₁₂ aryl group which may have a substituent, a C₂₋₁₀alkenyl group which may have a substituent, or a C₃₋₁₀ cycloalkyl groupwhich may have a substituent, a C₁₋₆ alkyl group, a C₁₋₆ alkoxy group,and a halogen atom.
 3. The metal chelate compound according to claim 1,wherein the residue D in the formula (I) is the one selected from thegroup consisting of residues represented by the following formulas:##STR186## wherein ring E may have a substituent, each of thesubstituent of ring E, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ which areindependent from one another, is a C₁₋₂₀ alkyl group, a C₃₋₁₀ cycloalkylgroup which may be substituted by a C₁₋₂₀ alkyl group, a C₁₋₂₀ alkoxygroup, a nitro group, a cyano group, --COOR¹⁷, wherein R¹⁷ is a C₁₋₂₀alkyl group, a C₃₋₁₀ cycloalkyl group which may have a substituent, or aphenyl group which may have a substituent, a phenyl group which may besubstituted by a C₁₋₂₀ alkyl group or a C₁₋₂₀ alkoxy group, a C₁₋₁₀alkylsulfonyl group, a halogen atom, or a C₁₀₋₃ perfluoroalkyl group, nis a 1 or 2, and m is 1, 2 or
 3. 4. The metal chelate compound accordingto claim 1, wherein the substituent Y in the formula (I) is the oneselected from the group consisting of --OH, --SH, --COOH, --SO₂ H, --SO₃H, --NH₂, B(OH)₂, --PO(OH)₂, --NHR¹⁶, --NHCOR¹⁶ and --NHSO₂ R¹⁶ whereinR¹⁶ is a C₁₋₆ alkyl group, a C₁₋₆ alkoxy group, a phenyl group which maybe substituted by a halogen atom, or a C₁₋₆ alkyl group which may besubstituted by a halogen atom, or a salt thereof.
 5. The metal chelatecompound according to claim 1, wherein the dis-azo compound is a dis-azocompound represented by the following formula (II): ##STR187## whereinring B may be substituted by a C₁₋₆ alkyl group, a C₁₋₆ alkoxy group, ora halogen atom, X is a residue forming an aromatic group together withthe two carbon atoms to which it is bonded, D is an aromatic residuewhich may have a substituted, or a heterocyclic amine residue which mayhave a substituent, and Y' is --COOH, --SO₃ H, or a salt thereof.
 6. Themetal chelate compound according to claim 1, wherein the dis-azocompound is a dis-azo compound represented by the following formula(III): ##STR188## wherein ring B may be substituted by a C₁₋₆ alkylgroup, a C₁₋₆ alkoxy group, or a halogen atom, D is an aromatic residuewhich may have a substituent, or a heterocyclic amine residue which mayhave a substituent, Y' is --COOH, --SO₃ H, or a salt thereof, and eachof R¹ and R² which are independent from each other, is a hydrogen atom,a C₁₋₂₀ alkyl group which may have a substituent, A C₆₋₁₂ aryl groupwhich may have a substituent, a C₂₋₁₀ alkenyl group which may have asubstituent, or a C₃₋₁₀ cycloalkyl group which may have a substituent,and ring C may have a substituent.
 7. The metal chelate compoundaccording to claim 1, wherein the dis-azo compound is a dis-azo compoundrepresented by the following formula (IV): ##STR189## wherein ring B maybe substituted by a C₁₋₆ alkyl group, a C₁₋₆ alkoxy group, or a halogenatom, Y' is --COOH, --SO₃ H, or a salt thereof, each of R¹ and R² whichare independent from each other, is a hydrogen atom, a C₁₋₂₀ alkyl groupwhich may have a substituent, a C₆₋₁₂ aryl group which may have asubstituent, a C₂₋₁₀ alkenyl group which may have a substituent, or aC₃₋₁₀ cycloalkyl group which may have a substituent, and each of ring Cand ring E may have a substituent.
 8. The metal chelate compoundaccording to claim 1, wherein the dis-azo compound is a dis-azo compoundrepresented by the following formula (V): ##STR190## wherein X is aresidue forming an aromatic group together with the two carbon atoms towhich it is bonded, D is an aromatic residue which may have asubstituent, or a heterocyclic amine residue which may have asubstituent, Y is a group having active hydrogen, or a salt thereof, andR³ is a hydrogen atom, a C₁₋₆ alkyl group, a C₁₋₆ alkoxy group, ahalogen atom, or a C₁₋₁₂ aryl group.
 9. The metal chelate compoundaccording to claim 1, wherein the dis-azo compound is a dis-azo compoundrepresented by the following formula (VI): ##STR191## wherein D is anaromatic residue which may have a substituent, or a heterocyclic amineresidue which may have a substituent, each of R¹ and R² which areindependent from each other, is a hydrogen atom, a C₁₋₂₀ alkyl groupwhich may have a substituent, a C₆₋₁₂ aryl group which may have asubstituent, a C₂₋₁₀ alkenyl group which may have a substituent, or aC₃₋₁₀ cycloalkyl group which may have a substituent, R³ is a hydrogenatom, a C₁₋₆ alkyl group, a C₁₋₆ alkoxy group, a halogen atom, or aC₁₋₁₂ aryl group, and ring C may have a substituent.
 10. The metalchelate compound according to claim 1, wherein the dis-azo compound is adis-azo compound represented by the following formula (VII): ##STR192##wherein each of R¹ and R² which are independent from each other, is ahydrogen atom, a C₁₋₂₀ alkyl group which may have a substituent, a C₆₋₁₂aryl group which may have a substituent, a C₂₋₁₀ alkenyl group which mayhave a substituent, or a C₃₋₁₀ cycloalkyl group which may have asubstituent, R₃ is a hydrogen atom, a C₁₋₆ alkyl group, a C₁₋₆ alkoxygroup, a halogen atom, or a C₆₋₁₂ aryl group, and each of ring C andring E may have a substituent.